radiation oncologists perspective

1. Management of Rectal cancer

3. Transrectal ultrasound –EUS
 use for clinical staging.
 80-95% accurate in tumor staging
 70-75% accurate in mesorectal lymph
node staging
 Very good at demonstrating layers of
rectal wall
 Use is limited to lesion < 14 cm from
anus, not applicable for upper rectum,
for stenosing tumor
 Very useful in determining extension of
disease into anal canal (clinical
important for planning sphincter
preserving surgery)
Figure. Endorectal
ultrasound of a T3 tumor of
the rectum, extension
through the muscularis
propria, and into perirectal
fat.

4. CT scan
 Part of routine workup of patients
 Useful in identifying enlarged pelvic lymph-nodes and
metastasis outside the pelvis than the extent or stage of
primary tumor
 Limited utility in small primary cancer
 Sensitivity 50-80%
 Specificity 30-80%
 Ability to detect pelvic and para-aortic lymph nodes is
higher than peri-rectal lymph nodes.

5. Figure: Mucinous adenocarcinoma of the
rectum. CT scan shows a large
heterogeneous mass (M) with areas of
cystic components. Note marked luminal
narrowing of the rectum (arrow).
Figure: Rectal cancer with uterine
invasion. CT scan shows a large
heterogeneous rectal mass (M) with
compression and direct invasion into the
posterior wall of the uterus (U).

6. Magnetic Resonance Imaging (MRI)
 Greater accuracy in defining extent of rectal cancer
extension and also location & stage of tumor
 Also helpful in lateral extension of disease, critical in
predicting circumferential margin for surgical excision.
 Different approaches (body coils, endorectal MRI)

10. Stage Grouping

11. Stage and Prognosis
Stage 5-year Survival (%)
0,1 Tis,T1;No;Mo > 90
I T2;No;Mo 80-85
II T3-4;No;Mo 70-75
III T2;N1-3;Mo 60-70
III T3;N1-3;Mo 50-65
III T4;N1-2;Mo 25-45
IV M1 <10

12. Prognostic factors
 Good prognostic
factors
 Old age
 Gender(F>M)
 Asymptomatic pts
 Polypoidal lesions
 Diploid
 Poor prognostic
factors
 Obstruction
 Perforation
 Ulcerative lesion
 Adjacent structures
involvement
 Positive margins
 LVSI
 PNI
 Signet cell carcinoma
 High CEA
 Tethered and fixed
cancer

13. PRINCIPLES OF PATHOLOGIC
REVIEW
 The following parameters should be reported:
 Grade of the cancer
 Depth of penetration (T), the T stage, is based on
viable tumor.
 Acellular mucin pools are not considered to be
residual tumor in those cases treated with
neoadjuvant therapy.
 Number of lymph nodes evaluated and number
positive (N).

14.  Acellular mucin pools are not considered to be
residual tumor in those cases treated with
neoadjuvant therapy
 Status of proximal, distal, and circumferential
(radial) margins.
 A positive circumferential resection margin (CRM)
has been defined as ≤1 mm
 Neoadjuvant treatment effect
 Lymphovascular invasion
 Perineural invasion
 Extranodal tumor deposits

16. Treatment
Surgery Chemotherapy Radiotherapy

17. Surgery
 Surgery remains the mainstay of curative
treatment for carcinoma of the rectum
 Surgical management depends on the stage
and location of a tumor within the rectum.

18. GOAL
 The general principles of a surgical approach
remain the removal of all gross and microscopic
disease with negative proximal, distal, and
circumferential margins
 reserve intestinal continuity and the sphincter
mechanism whenever possible while still
maximizing tumor control

19.  Early cancers can be managed with limited
surgery
 majority of tumors tend to present as more
advanced disease
 require either a low anterior resection (LAR) or
abdominoperineal resection (APR).

20. Local Excision
 Polypectomy
 Transanal excision
 Transanal endoscopic microsurgery (TEM)
 patients need to be carefully selected for these
procedures

21. Transanal Excision
 selected T1, N0 early-stage cancers.
 Small (<3 cm)
 well to moderately differentiated tumors
 within 8 cm of the anal verge
 limited to less than 30% of the rectal
circumference
 no evidence of nodal involvement

22.  transanal excision and TEM involve a full-
thickness excision performed perpendicularly
through the bowel wall into the perirectal fat.
 Negative (>3 mm) deep and mucosal margins are
required, and tumor fragmentation should be
avoided.
 The excised specimen should be oriented and
pinned before fixation
 brought to the pathologist by the surgeon to
facilitate an oriented histopathologic evaluation of

23.  Advantages of a local procedure include minimal
morbidity (eg, a sphincter-sparing procedure) and
mortality
 rapid postoperative recovery.
 If pathologic examination reveals adverse
features
 positive margins, LVI, poor differentiation, or
invasion into the lower third of the submucosa
 a more radical resection is recommended

24.  Limitations of a transanal excision include the
absence of pathologic staging of nodal
involvement
 lymph node micrometastases are both common in
early rectal lesions and unlikely to be identified by
endorectal ultrasonogram or MRI
 A recent retrospective study of 282 patients
undergoing either transanal excision or radical
resection for T1 rectal cancer from 1985 to 2004
 showed respective local recurrence rates of
13.2% and 2.7% for these 2 groups

25. Transabdominal Resection
 Abdominoperineal Resection
 APR has been considered the gold standard for
surgical resection of distal rectal cancer located within
6 cm of the anal verge.
 This procedure requires a tranabdominal as well as a
transperineal approach with removal of the entire
rectum and sphincter complex.
 A permanent end colostomy is created and the
perineal wound either closed primarily or left to
granulate in after closure of the musculature

26.  APR is associated with a slightly higher morbidity and
mortality than LAR
 a worse quality of life related to changes in body
image and depression due to the presence of a
colostomy
 There is also a higher risk of positive margins with
APR as the mesorectum is very thin in the distal
segment of the rectum
 lateral margins are restricted by the close presence of
the prostate in the male and vagina in females
 The bony confines of the lower pelvis also restrict
surgical access especially in males.

27. Low Anterior Resection
 The availability of circular stapling devices has
expanded the role of sphincter preservation
surgical options in rectal cancers
 LARs are now being performed not just for
cancers of the upper third of the rectum but also
for middle and lower third cancers
 Preserving adequate anorectal function becomes
a bigger problem the more distal the level of
anorectal anastomosis

28.  Patients should have good anal sphincter
continence prior to considering sphincter-
preserving options
 A 2-cm distal margin of preserved normal rectum
is considered optimal for preservation of good
bowel function.
 In carefully selected patients a functional coloanal
anastomosis can be achieved with significantly
reduced margins for more distal cancers
especially after neoadjuvant therapy.

29.  Advances in stapling instruments have been very
important as aids in reconstruction.
 Narrow, low-profile staplers allow the surgeon to
place a staple line across the rectum at the level
of the anorectal ring or below.
 This, combined with the circular stapler, allows
the surgeon to construct a quick and reliable
“double-stapled” anastomosis even at the level of
the anal canal.

31. Total Mesorectal Resection
 In the rectum the mesorectum is the structure that
contains the blood supply and lymphatics for the
upper, middle, and lower rectum.
 Most involved lymph nodes for rectal cancers are
found within the mesorectum
 T1 lesions associated with positive lymph nodes
in 5-7%
 T2 -20%
 T3 -65%
 T4-78%

32.  Bill Heald from
Basingstoke,
England, 1982, first
began to write about
his technique of TME
 He recognized that
most local
recurrences seen
after rectal cancer
resection were a
result of inadequate
resections performed
using imprecise, blunt

33.  He recognized that by using meticulous, sharp
dissection, under direct vision
 staying between the visceral and parietal pelvic
fascia down to the level of the levators, or upper
aspect of the anal canal
 the rectum and its mesentery could be removed
as an intact unit

34.  A TME involves an en bloc removal of the
mesorectum, including associated vascular and
lymphatic structures, fatty tissue, and mesorectal
fascia as a “tumor package”
 through sharp dissection and is designed to spare the
autonomic nerves
 After a TME the specimen is typically shiny and
bilobed in contrast to the irregular and rough surface
after a blunt dissection where much of the mesorectal
fat is left behind.
 TME attempts not only to clear involved lymph nodes

35.  Distal mucosal margins of 1 cm or greater are
adequate for local control
 however, the margin on the mesorectum should
extend beyond the distal mucosal margin in order
to ensure a successful surgical outcome.
 positive CRM as tumor within 1 mm from the
transected margin

37. 786 patients from August 1993 to July 2002. Of these,
622 patients (395 men and 227 women; median age, 67
years) underwent anterior resection.
mid and distal rectal cancer were treated with TME
The local recurrence rate was 9.7% and the cancer-
specific survival was 74.5%.

38. Laparoscopic Resection
 The phase III COLOR II trial, powered for
noninferiority
 randomized patients with localized rectal cancer to
laparoscopic or open surgery.
 patients in the laparoscopic arm lost less blood, had
shorter hospital stays, and had a quicker return of
bowel function,
 had longer operation times.
 No differences were seen in completeness of
resection, percentage of patients with positive CRM,

39. Role of Combined Modality
Therapy
 Older studies demonstrate local failure rates of up
to 50% in patients with T3-4 or N+ disease
 Local failure is related not just to the stage of the
disease
 but also the location of the tumor in the rectum
 experience and ability of the surgeon.

40.  initial studies reported local-regional failure rates
of less than 5% after TME without the use of any
adjuvant therapy
 there was concern that these excellent results
could not be replicated in larger population-based
studies
 As most of surgeries done even now are not
proper TME

41. Adjuvant therapy
Chemotherapy
Radiation therapy
with or without
chemotherapy

42. Adjuvant Therapy
 The problem of unacceptably high local
recurrence after surgery has led to many studies
exploring the potential benefit of postoperative
adjuvant therapy
 Advantages of postoperative radiation
 ability to selectively treat patients at high risk of
local failure on the basis of pathologic stage

43.  Disadvantages
 potentially hypoxic postsurgical bed, making
radiation less effective
 higher complications due to increased small
bowel in the radiation field
 a larger treatment volume, especially if the patient
undergoes an APR and the perineal scar needs
to be covered

44.  There have been several large trials of
postoperative radiation with or without
chemotherapy.
 In general, surgery alone has resulted in a 25%
local failure rate and 40% to 50% overall survival
for T3 or T4 or node-positive patients
 while radiation with the addition of chemotherapy
has yielded a lower local failure rate of 10% to
15% and higher overall survival rate of 50% to
60%.

45. Earlier studies
 NSABP R-01study (randomized 555 patients
into three arms after surgery: (a) observation, (b)
postoperative chemotherapy of eight cycles of
MOF (5FU, CCNU [semustine], and vincristine),
and (c) postoperative radiation treatment alone of
46 to 47 Gy
 Postoperative chemotherapy improved disease-
free survival but not overall survival.
 Postoperative radiation treatment trended toward
improved local control but not overall survival

46. NSABP R-02 study
 enrolled 694 stage B and C patients
 asked two questions in its study design
 (a) Does the addition of radiation to
chemotherapy improve outcome?
 (b) Is MOF superior to 5-FU/LV
 The radiation dose was 50.4 Gy.

47.  At 5 years, the LRF was 13% for the
chemotherapy VS 8% with the addition of
radiation and chemotherapy.
 5-FU/LV showed better relapse-free survival and
disease-free survival but not overall survival as
compared to MOF
 Conclusion of 2 NSABP trials- while postoperative
radiation treatment did not appear to improve
overall survival

48.  Gastrointestinal Tumor Study Group (GITSG)
 North Central Cancer Treatment Group (NCCTG)
studies
 show an improvement in survival

49. GITSG study
 four-arm trial of 227 patients with stage B2 and C
rectal cancer who were randomized to either
 (a) surgery alone
 (b) postoperative chemotherapy of bolus 5-FU (500
mg/m2 in weeks 1 and 5 and methyl-CCNU
(semustine given day 1)
 (c) postoperative radiation treatment of 40 to 48 Gy
split course
 (d) postoperative chemotherapy and radiation therapy

50.  In a 9-year update
 Post op CRT improved the overall survival to 54%
versus 27% with observation after surgery.
 There was a prolonged time to recurrence and a
decreased recurrence rate of 33% versus 55%.
 Local failure rate was decreased to 10% versus
25% with surgery alone

51. Mayo-NCCTG
 Compared postoperative radiation therapy against
postoperative radiation therapy and chemotherapy
 The 5-year local regional failure was higher in the
radiation only arm of 25% versus 15%
 5-year overall survival rate was 40% versus 55%.
 reduced local recurrence by 46% and distant
metastases by 37%.
 Cancer deaths were reduced by 36%, and overall
deaths were reduced by 29%.

52. Ideal chemotherapeutic agent?

53. Intergroup 0114 study
 (a) bolus 5-FU alone
 (b) 5-FU and leucovorin
 (c) 5FU plus levamisole
 (d) 5-FU and leucovorin plus levamisole.
 The radiation treatment dose was 45 Gy with a
5.4- to 9-Gy boost to a total of 50.4 to 54 Gy.

54.  With a median follow-up of 7.4 years
 there was no difference in overall survival or
disease-free survival among the four groups.
 The three-drug regimen had a greater toxicity.
 Levamisole and leucovorin did not appear to add
any benefit to the 5-FU.

55. NEO ADJUVANT THERAPY
 Due to potential disadvantages of post op RT
 potentially hypoxic postsurgical bed, making
radiation less effective
 higher complications due to increased small
bowel in the radiation field
 a larger treatment volume, especially if the patient
undergoes an APR and the perineal scar needs
to be covered

56.  Although both pre- and postoperative adjuvant
therapy can be effective
 there has been a significant recent trend toward
greater use of neoadjuvant treatment
 Tumor down staging, improved resectability, and
potential for expanded sphincter preservation
options in the distal rectum also encourages

57.  Studies from Europe have demonstrated that
appropriate neoadjuvant preoperative radiation
results in improvement of both local control and
survival
 these results have had a significant impact on the
current management of this disease

58. NEOADJUVANT RADIATION

59.  Main flaw of study is that the surgery alone arm
did not utilize TME
 which may have resulted in an unacceptably high
local failure rate of 27%
 Late effects suggested more bowel movement
frequency, incontinence, urgency, and soiling in
the preoperative radiation treatment arm,
although overall quality of life was rated good

60.  the dose of 5 Gy times five fractions may induce
significant acute and late toxicity
 the short interval between radiation and surgery
may not have allowed sufficient time for tumor
regression (downstaging) for improved sphincter
preservation.

61. TME alone is required?
 A Dutch (CKVO 95-04) multicenter, phase III
study
 1,861 patients was undertaken to evaluate the
role of short course preoperative radiation with
TME.
 TME alone versus 25 Gy in five fractions followed
by TME surgery
 No fixed tumors were included in the study, and
half of the patients had T1 or T2 disease

62. RESULTS
 The OS was same (82% at 2 years).
 However the local recurrence at 2 years was
8.2% in the TME-only arm as compared to 2.4%
in the preoperative arm
 This study highlighted the value of radiation
treatment, even with TME
 The sphincter preservation rate was the same in
both arms
 and there was no clear evidence of any

63.  The perineal complication rate was slightly higher
in the preoperative radiation arm of 26% versus
18%.
 A more recent update indicates a higher
incidence of sexual dysfunction and slower
recovery of bowel function
 More fecal incontinence and generally poorer
quality of life with short-course preoperative
radiation

64. META ANALYSIS
 Two meta-analyses of approximately 6,000
patients each were done to explore the benefit of
preoperative radiation treatment
 They noted a significant reduction in the risk of
local recurrence and death from rectal cancer
with preoperative radiotherapy

65. Neoadjuvant Chemoradiation
 The improvement in outcomes with combined
chemoradiation and postoperative adjuvant
therapy has led to similar recent approaches in
the neoadjuvant therapy of this disease

66. French study FFCD 9203
 Patients with resectable T3 and T4 tumors were
randomized to 45 Gy of radiation alone
 versus radiation with concurrent bolus 5-FU (350
mg/m2) plus leucovorin on days 1 to 5 during
weeks 1 to 5
 After surgery, four cycles of adjuvant
chemotherapy were given.
 With a median follow-up of 69 months, there was
an equivalent rate (51%) of sphincter-sparing

67.  Combined treatment led to improved PCR rate of
11.4% versus 3.6%
 improved 5-year local failure rate of 8% versus
16.5%.
 There was, however, no difference in overall
survival

69. SHORT COURSE VS LONG
COURSE RT
 Polish rectal cancer group
 (5 Gy for five fractions) VS 50.4 Gy using 1.8 to
2 Gy fractions with concomitant bolus 5-FU and
leucovorin given during weeks 1 and 5
 higher PCR was seen with chemoradiation (16%
vs. 1%), fewer positive radial margins (4% vs.
13%), and considerably reduced size of the tumor
by approximately 1.9 cm
 no difference in the rate of sphincter preservation,
local control or survival was seen.

70. Preoperative Versus
Postoperative
 The definitive phase III study in favor of
preoperative radiation therapy was the
CAO/ARO/AIO-94 study performed by the
German Rectal Cancer group

71. Schema of the German rectal cancer
trial

72. RESULTS
 The 5-year results revealed a pelvic recurrence
ratio of 6% versus 13% (p = 0.02) in favor of the
preoperative arm.
 No differences in DFS ,OS, or distant failures
 There was significant tumor downstaging with an
8%PCR.
 Nodal positivity was 25% VS 40%

73.  sphincter-preserving low anterior resection 39%
versus 19% had a (p = 0.004)
 There were fewer acute (27% vs. 40%) and late
toxicities (14% vs. 24%) in preoperative-treatment
group
 WITH THIS EVIDENCE PRE OP CHEMO
RADIATION HAS BECOME THE STANDARD OF
CARE FOR OPERABLE T3/T4/N+ RECTAL
CANCERS

74. Locally Advanced Rectal Cancer
 Clinical T4 tumors may not be resected
completely due to tumor fixation.
 Preoperative radiation treatment is recommended
to facilitate curative resections
 M.D. Anderson investigators demonstrated that
preoperative chemotherapy and radiation therapy
increased overall survival (80% vs. 60%), local
control (95% vs. 66%), and the number of
sphincter preserving procedures (35% vs. 7%) as
compared to radiation alone

75. IORT
 Preoperative continuous infusion 5-FU plus 50.4
to 54 Gy of radiation was given followed by a 4-
to 6-week break and surgery.
 IORT-Ten to 12.5 Gy were given for complete
resection
 12.5 to 15 Gy for microscopic residual
 17.5 to 20 Gy for gross residual disease.

76.  No IORT was given if metastases were present at
surgical exploration
 if there were adequate margins >1 cm
 if there was less than T4 disease.
 IORT improves local control, especially with a
gross total resection, but not survival for locally
advanced rectal cancer

77. Adjuvant Chemotherapy
 Adjuvant chemotherapy is recommended for all
patients with stage II/III rectal cancer
 following neoadjuvant chemoRT/surgery
regardless of the surgical pathology results
 A recent systematic review and meta-analysis of
9785 patients with nonmetastatic rectal cancer
from 21 randomized controlled trials from 1975
until March 2011
 concluded that OS and DFS are improved with
the addition of postoperative 5-FU–based therapy

78.  Most of the support for use of FOLFOX or
capecitabine as adjuvant chemotherapy in rectal
cancer is an extrapolation from the data from
colon cancer
 The use of a shorter course of adjuvant FOLFOX
in rectal cancer (ie, 4 months) is justified when
preoperative chemoRT is administered.

81. Management of Metastatic Disease
 Approximately 50% to 60% of patients diagnosed
with colorectal cancer will develop metastases
 synchronous metastatic colorectal liver disease is
associated with a more disseminated disease
state and a worse prognosis
 than metastatic colorectal liver disease that
develops metachronously.

82.  Factors associated with a poor prognosis in
patients with colorectal cancer
 the presence of extrahepatic metastases
 the presence of more than 3 tumors
 a disease-free interval of fewer than 12 months
 retrospective analyses and meta-analyses have
shown that patients with solitary liver metastases
have a 5-year OS rate as high as 71% following
resection.

83. CRITERIA FOR RESECTABILITY OF METASTASES
AND LOCOREGIONAL THERAPIES WITHIN
SURGERY
 Hepatic resection is the treatment of choice for
resectable liver metastases from colorectal cancer.
 Complete resection must be feasible based on
anatomic grounds and the extent of disease;
 maintenance of adequate hepatic function is required
 The primary tumor must have been resected for cure
(R0).
 There should be no unresectable extrahepatic sites of
disease.Plan for a debulking resection (R1/R2
resection) is not recommended.

84.  Patients with resectable metastatic disease and
primary tumor in place should have both sites
resected with curative intent.
 These can be resected in one operation or as a
staged approach

89. RADIOTHERAPY

90. INDICATIONS
 T3/T4 lesion
 Node positive disease
 Inoperable disease
 Palliation of symptoms

91. TARGET VOLUME
 External-beam treatment portals for rectal carcinoma
should always encompass the sites at greatest risk:
 The presacral space
 the primary tumor site, and the perineum (for post-
APR cases)
 The mesorectal and lateral lymph nodes and internal
illiac are included in all patients
 The external iliac nodes should be covered for T4
lesions.

92.  The inguinal lymph nodes may be included
 if tumour invades the lower third of the vagina
 if there is major tumour extension into the internal
and external anal sphincter

93. RADIATION TECHNIQUES
 Patients may be treated supine or prone
 though placing the patient prone with a belly
board may help move small bowel out of the
pelvis.
 A rectal marker or rectal contrast can help
delineate the location of the tumor
 wire perineal scar if present
 small bowel contrast

94. Belly board

96. Fields
 2 field technique
 3 field
 4 field

97. Conventional Field borders
Whole pelvic field:
 A : Posterior-anterior
Superior border: L5-S1 junction
Distal border: 3 cm below the primary tumor or at the
inferior aspect of the obturator foramina, whichever is the
most inferior
Lateral borders: 1.5 cm lateral to the widest bony margin
of the true pelvic side walls.

98.  B : Laterals
Anterior border:
T3 disease: Posterior margin of the symphysis pubis
(to treat only the internal iliac nodes).
T4 disease: Anterior margin of the symphysis pubis (to
include the external iliac nodes
Posterior border: 1 to 1.5 cm behind the anterior bony
sacral margin

99.  After an abdominoperineal resection:
A :Wire the perineal scar and create a 1.5-cm
margin beyond the wire in all fields.
 Boost field:
A : Treat the primary tumor bed plus a 3-cm
margin (not the nodes).

100. Fig B: For a T4N1M0 rectal
cancer 8 cm from the anal
verge. Since the tumor was a
T4, the anterior field is at the
anterior margin of the
symphysis pubis (to include
the external iliac nodes).
Fig A: Treatment fields after a low anterior
resection for a T3N1M0 rectal cancer 8 cm
from the anal verge. The distal border is at
the bottom of the obturator foramen and the
perineum is blocked. Since the tumor was a
T3, the anterior field is at the posterior
margin of the symphysis pubis (to treat only
the internal iliac nodes).
Fig C: Treatment fields following an
abdominoperineal resection for a T4N1M0
rectal cancer 2 cm from the anal verge,
because the tumor was a T4, the anterior
field is at the anterior margin of the
symphysis pubis (to include the external
iliac nodes). Since the distal border is
being extended only to include the scar
and external iliac nodes, the remaining
normal tissues can be blocked

101. Isodose curves for 3 field

102. Isodose curves for 4 field

103. 3 D CONFORMAL RT

104.  CT based treatment planning is preferred to
ensure adequate coverage of the tumor and
regional nodes and improve dose homogeneity
 Planning CT should be taken from the level of mid
abdomen (L1) to level of mid thigh with 5mm cut
 Iv, rectal and bowel contrast will clearly defining
target as well as critical structures
 Fusion of the treatment planning CT with other
imaging modalities MRI or PET may also help
identify the tumor location

105.  The GTV includes all gross tumour seen on the
planning CT scan with reference to information
from diagnostic endoscopy, MRI and DRE
 Any involved lymph nodes, extrarectal extension,
or extranodal deposits seen on MRI should be
included
 CTV should include peri-rectal, pre-sacral,
internal iliac regions

106. RTOG GUIDELINES
 The caudad extent of this elective target volume
should be a minimum of 2 cm caudad to gross
disease, including coverage of the entire
mesorectum to the pelvic floor
 The posterior and lateral margins of CTV should
extend to lateral pelvic sidewall musculature or,
where absent, the bone
 Anteriorly, the group recommended extending 1
cm into the posterior bladder, to account for day-
to-day variation in bladder position.

107.  The recommended superior extent of the peri-
rectal component
 the rectosigmoid junction or 2 cm proximal to the
superior extent of macroscopic disease in the
rectum/peri-rectal nodes.
 To include illiac vessels it should be kept at L5/S1
JUNCTION

108.  Margin around blood vessels:
 The group recommended a 7-8 mm margin in
soft tissue around the external iliac vessels
 but one should consider a larger 10+ mm
margin anterolaterally IF nodes are identified
in this area

109. BOOST VOLUME
 The group did recommend that any boost clinical
target volumes extend to entire mesorectum and
presacral region at involved levels
 including ~2 cm cephalad and caudad in the
mesorectum and ~2 cm on gross tumor within the
anorectum.
 PTV margin should be ~0.7 to 1.0 cm, except at
skin

114. Techniques to Decrease Radiation
Toxicity in Small Bowel
 High-energy (>6 MV) linear accelerators.
 Treatment 5 days per week and all fields each
day.
 Port films once per week or more often if clinically
indicated
 Pelvic field: multiple-field technique (posterior-
anterior plus laterals or posterior-anterior-anterior-
posterior plus laterals) is recommended.

115.  Boost field: opposed laterals.
 Computerized dosimetry optimizing between
minimizing the lateral hot spots and small bowel
dose and increasing the homogeneity within the
target volume
 In thin patients, a combination of 6 MV for the
posterior fields and higher-energy photons for the
lateral fields may result in more homogeneous
dosimetry.
 Shaped blocks and, if needed, wedges on the
lateral fields.
 Small bowel contrast. Shield as much small bowel

116.  Rectal contrast. Barium sulfate is injected with a Foley
catheter. A wire is placed on the catheter to indentify
the anal verge
 Prone position.
 Full bladder, only if it does not make the patient so
uncomfortable as to cause movement.
 The entire perineum can be blocked after a low
anterior resection
 Immobilization molds (belly boards) and abdominal
wall compression may be helpful

117. Intensity-Modulated Radiation
Therapy
 may offer the potential to reduce toxicity
 but there are no set standards regarding its use
 Different IMRT volume–based dose constraints
have been proposed for bowel and bladder, but
there is no set consensus.
 IMRT-based sparing of the iliac crests may also
reduce bone marrow toxicity

118.  Currently, IMRT is not recommended for routine
use.
 IMRT can be used in re irradiation for recurrence

120. endocavitary radiation therapy.
 T1 or T2 tumors less than 3 cm
 not poorly differentiated
 with no evidence of nodal involvement.
 Patients are treated with a special low energy x-
ray machine (50 kVp) that is attached to a rigid
endoscopic-type device that can be placed in the
rectum directly over the tumor.
 As the opening of the applicator is 3 cm, it is
difficult to treat tumors larger than this.

121.  Patients typically receive four treatments of 2,500 to 3,000
cGy each with 2 to 3 weeks between treatments to allow
for tumor regression.
 Although the total dose is extremely high, the minimal
penetration of the radiation beam protects the underlying
normal tissue.
 Local control results with this approach have been very
good in properly selected patients
 but specialized equipment is required (which is not
generally available)
 less pathological information is obtained than after a local
excision.
 This approach is rarely used at the present time

122. Dose
 Preoperative radiotherapy
 Short course: 25 Gy in 5 daily fractions of 5 Gy given in 1
week.
 Long course
Phase 1
45 Gy in 25 daily fractions of 1.8 Gy given in 5 weeks.
Phase 2
5.4 in 3 daily fractions of 1.8 Gy
 Postoperative radiotherapy
Phase 1
45 Gy in 25 daily fractions of 1.8 Gy given in 5 weeks.
Phase 2
5.4–9 Gy in 3–5 daily fractions of 1.8 Gy.

123. Adverse effects
 Acute complications
 diarrhea and increased bowel frequency (small
bowel)
 acute proctitis (large bowel)
 thrombocytopenia, leukopenia, and dysuria are
common during treatment.
 These conditions are usually transient and
resolve within a few weeks following the
completion of radiation.

124.  In the small bowel, loss of the mucosal cells
results in malabsorption of various substances,
including fat, carbohydrate, protein, and bile salts.
 The bowel mucosa usually recovers completely in
1 to 3 months following radiation.
 Management usually involves the use of
antispasmodic and anticholinergic medications.

125. Delayed complications
 occur less frequently, but are more serious.
 The initial symptoms commonly occur 6 to 18 months
following completion of radiation.
 persistent diarrhea and increased bowel frequency
 proctitis, small bowel obstruction (SBO) not requiring
surgery,
 perineal and scrotal tenderness,

126.  delayed perineal wound healing
 urinary incontinence
 bladder atrophy and bleeding.